When consumers launder fabrics, they desire not only excellence in cleaning, they also seek to impart superior fabric care benefits via the laundering process. Such fabric care benefits to be imparted can be exemplified by one or more of reduction, prevention or removal of wrinkles; the improvement of fabric softness, fabric feel or garment shape retention or recovery; improved elasticity; ease of ironing benefits; color care; anti-abrasion; anti-pilling; or any combination of such benefits. Detergent compositions which provide both fabric cleaning performance and additional fabric care effects, e.g., fabric softening benefits, are known as “2-in-1”-detergent compositions and/or as “softening-through-the-wash”-compositions.
Due to the incompatibility of anionic detersive surfactants and many cationic fabric care agents, e.g., quaternary ammonium fabric softening agents, in liquid detergent compositions, the detergent industry has formulated alternative compositions which utilize fabric care agents which are not necessarily cationic in nature. One such type of alternative fabric care agents comprises silicone, i.e., polysiloxane-based, materials. Silicone materials include nonfunctional types such as polydimethylsiloxane (PDMS) and functionalized silicones, and can be deposited onto fabrics during the wash cycle of the laundering process. Such deposited silicone materials can provide a variety of benefits to the fabrics onto which they deposit. Such benefits include those listed hereinbefore.
Non-functionalized silicones, however good in their compatibility with detergents, have shortcomings. Such non-functionalized silicones can produce excellent fabric care benefits when directly applied to textiles, yet are found to work ineffectively in liquid laundry detergents. The problem is a complex one and includes inadequate deposition in the presence of surfactants, unsatisfactory spreading, inadequate emulsion stability and other factors. When such non-functional materials do not deposit effectively, a major proportion of the silicone is lost to the drain at the end of the wash, rather than being deposited evenly and uniformly on the fabrics, e.g., clothing, being washed.
One specific type of silicones which can provide especially desirable deposition and fabric substantivity improvements comprises the functionalized, nitrogen-containing silicones. These are materials wherein the organic substituents of the silicon atoms in the polysiloxane chain contain one or more amino and/or quaternary ammonium moieties. The terms “amino” and “ammonium” in this context most generally means that there is at least one substituted or unsubstituted amino or ammonium moiety covalently bonded to, or covalently bonded in, a polysiloxane chain and the covalent bond is other than an Si—N bond, e.g., as in the moieties —[Si]—O—CR′2—NR3, —[Si]—O—CR′2—NR3, —[Si]—OCR′2—N+R4, —[Si]—OCR′2—N+HR2, —[Si]—O—CR′2—N+HR2, —[Si]—CR′2—NR3 etc. where —[Si]— represents one silicon atom of a polysiloxane chain. Amino and ammonium functionalized silicones as fabric care and fabric treatment agents are described, for example, in EP-A-150,872; EP-A-577,039; EP-A-1,023,429; EP-A-1,076,129; and WO 02/018528.
Functionalized, nitrogen-containing silicones such as these can be used in and of themselves to impart a certain amount and degree of fabric care benefit. However such functionalized silicones also have shortcomings. For example it is known that they can react chemically with components of detergents. Mechanisms of reaction have not been well documented but can in principle include reactions of aminofunctional groups themselves, as well as reactions of curable groups present within such functionalized polymers. The art is ambivalent on the possibility of successfully including reactive or curable silicones in detergents without stability problems. On one hand there are references teaching desirablity of having curable or reactive moieties, and on the other hand there are references teaching desirability of avoiding all reactive moieties (in this context including ammonium or aminofunctional moieties) in various cleaning compositions.
Functionalized, nitrogen-containing silicone materials useful as fabric care agents can be prepared from nitrogen-substituted alkoxysilanes or alkoxysiloxanes as starting materials. (See for example, the processes disclosed in EP-A-269,886 and U.S. Pat. No. 6,093,841.) Such preparation can involve hydrolysis of the starting materials followed by catalytic equilibration and condensation with non-functionalized siloxanes. Depending on the process involved and conditions used, the resulting amino or ammonium functionalized silicones will contain reactive groups on the silicon atoms, and especially the terminal silicon atoms, of the siloxane chains in such reaction product material. Such reactive groups can comprise —H, —OH, and —OR moieties originally present in the silane and siloxane starting materials. In view of the state of the art it is not currently possible to predict what overall structures, and what levels of reactive groups in particular, can be accommodated in a stable and effective fabric-care-benefit-providing liquid laundry detergent composition. Yet, it would be highly desirable to solve this problem in order that synthesis routes such as the above, found desirable for manufacturing reasons, can be applied to the provision of improved fabric care detergents.
Processes which remove reactive groups from the functionalized silicone end product serve to render those end products “nonreactive.” However, it is desirable to conduct such additional processes only to the minimum extent required for good liquid detergent fabric care benefit performance and stability, or the processes are wasteful and costly. The problem of determining the correct composition of miscible blends of silicones in terms of structure and in terms of parameters such as nitrogen content and reactive group content so as to select preferred fabric care liquid laundry detergents has now been solved.
It has now been determined what concentrations of residual reactive groups can cause problems when the resulting functionalized silicone materials are used as, or as part of, fabric care agents in liquid detergent compositions. The use of silicones containing these reactive group concentrations leads to deactivation of the functionalized silicones themselves and/or to deactivation of other components of the liquid detergent compositions. Use in liquid detergents of functionalized silicones with significant levels of reactive groups can also lead to formation of higher molecular weight, higher viscosity, or unspreadable polymeric materials upon storage of the liquid detergent products and this in turn leads to severe reduction or even loss of fabric care benefits either immediately or on storage and with passage of time.
It has now been discovered that such problems can be negated or minimized by using in liquid laundry detergent products droplets of a silicone blend of preferably miscible silicones comprising certain amino and ammonium functionalized silicone material in combination with certain kinds of non-functionalized polysiloxanes. The amino and ammonium functionalized silicones used are those which have been prepared in a manner to minimize the presence therein of certain types of reactive moieties. These selected amino and ammonium functionalized silicones are also those which have a specific balance of amine and/or ammonium functionality, as quantified by nitrogen content, and silicone viscosity and preferably molecular weight. Without being limited by theory, the nitrogen content is fundamentally linked to the ability to obtain miscibility of the functionalized and non-functionalized silicones, and the blend combination of the two acts synergistically. Moreover, while the levels of reactive group content needed are low, they do not need to be zero. This is believed to be due, at least in part, to the ability of the non-functionalized silicone to protect the functionalized silicone from interaction with other components of the detergent composition. Furthrmore, use of combinations of functionalized and non-functionalized silicones also permits formulation of liquid detergent products which do not need to contain a cationic deposition aid or a coacervate phase-forming polymer in order to promote deposition of the silicone materials onto fabrics.
The present invention therefore offers numerous advantages. First, an improved aqueous liquid laundry detergent having excellent fabric care benefits, especially softness and handle, is obtained. Second, use of wasteful levels of silicones is avoided. Third, the more expensive and complex functionalized silicones can be used at reasonable levels. Fourth, the compositions are stable and effective for their intended industrial purposes. Other advantages include that the compositions are non-yellowing on white textiles and moreover, that they do not give uneven deposition or lead to unacceptable visual results on clothing.